Bags and luggage have become a necessity in our everyday lives, such as backpacks (student backpacks and outdoor backpacks), travel boxes, briefcases, lady handbags, shoulder bags and so on. With the constant development of our society, diverse portable digital devices are emerging in our lives, and we rely more and more on them, including tablet computers, cellphones, digital cameras, video cameras and the like. In addition to containing the stuff, people want more functionality from the bags and luggage. For example, charging the portable digital devices. Especially for tourists, field staff and those making long-term business trips, it is not easy to charge their digital devices when the battery is dying, causing a lot of inconvenience and trouble in their works and lives. The present bags and luggage are equipped with no charging function, or a portable power source is provided in a bag or luggage for charging. It is necessary to open the bag or luggage for charging, which is quite inconvenient.